ANCA – panel

Indication

Suspicion of autoimmune hepatitis, ulcerative colitis, rheumatoid arthritis, cystic fibrosis or for the follow-up of positive samples of indirect immunofluorescence that are negative for PR3- and MPO-ANCA.

Method

ELISA with the purified proteins azurocidin, BPI (CAP57), cathepsin G, elastase, lactoferrin and lysozyme as antigen. These proteins are mainly found in granules in myeloid cells or as granulocytes and monocytes and participate in the body’s inflammation defence by killing bacteria through the enzymatic function and the formation of oxygen radicals.

Answer

The result is given as a ratio between patient serum and normal serum.

Reference range

3 with a borderline value of 4.

Interpretation

These antibodies rarely occur in systemic vasculitis but more often in ulcerative colitis, Crohn’s disease, primary sclerosing cholangitis, autoimmune hepatitis, rheumatoid arthritis, Felty’s syndrome and cysticfibrosis. The pathogenic importance is unknown. However, the antibodies also occur in systemic lupus erythematosus and therefore cannot be regarded as diagnostically very interesting except in particular patients. In a few patients with systemic vasculitis these antibodies occur at varying degrees, but they are not diagnostic whereas PR3- and MPO-ANCA are the most common and are of great diagnostic importance.

The ANCA expanded analysis is important for the follow-up of samples that are positive at indirect immunofluorescence analysis and that at the same time are negative for PR3- and MPO-ANCA. The reason is that the same pattern may arise from several different antibodies. Anti-MPO can, for instance, sometimes give a C-ANCA pattern. Anti-BPI can give both C- and P-ANCA staining, whereas anti- PR3 usually gives a C-ANCA pattern. With a positive IIF result it is therefore always necessary to verify it with a specific analysis, such as ELISA, as a pattern may arise from different antibodies but only PR3-ANCA and MPO-ANCA are of interest for the diagnosis of systemic vasculitis.

Patients with RA have ANCA and particularly those with Felty’s syndrome but the antigens are unknown and the IIF pattern is often called GS-ANA because of the dominant nuclear staining. About half the patients with ulcerative colitis have P-ANCA with mostly unknown antigens. These ANCA also occur in Crohn’s disease at lower frequencies. In sclerosing cholangitis lactoferrin ANCA in particular has been reported. P-ANCA also occurs in autoimmune hepatitis, again with unknown antigens. BPI-ANCA is of interest in cystic fibrosis investigations, as BPI-ANCA is a marker for pseudomonas infection and the level of the antibody correlates with the lung function. ANCA with a specificity for MPO, elastase, lactoferrin etc also occurs in association with drug induced conditions, e g hydralazine and propylthiouracil. Anti-elastase has been reported in connection with cocaine abuse. (14-23).

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Packages and other tests

View other packages Cystic fibrosis (536), Inflammatory bowel diseases (IBD) (513). View other tests ANCA IIF, BPI-ANCA – IgG and IgA

20 years experience